Process of making aromatic hydrocarbons.



s'rarss Parana curios.

CLIVE M. ALEXANDER, OF PORT ARTHUR, TEXAS, ASSIGN OR TO GULF REFINING COM- PANY, PITTSBURGH, PENNSYLVANIA, A CORPORATION OF TEXAS.

' r'nocnss or MAKING ARQMATIC HYDROCARBONS.

1,230,975. No Drawing.

To all whom it may concern:

Be it known thatI, CLIVE M. ALEXANDER, I

the following is aspecification.

This invention relates to processes of making aromatic hydrocarbons; and it comprises a method off-producing the lower boiling aromatic hydrocarbons, such as toluene and benzene (benzol) from the higher-boiling aromatic hydrocarbon materials such as the higher boiling tar oils, and particularly from the commercial grade known as solvent naphtha, wherein such higher boiling oils are transmitted in vapor form through a retort or tube heatedlto a temperature of from 600 to 1,000 (1, but best around 800 (lat a rate sufficiently rapid to give a liquid condensate of around 70 per cent. of the original volume of the oil treated and sufliciently rapid to 'give a substantial proportion of high-boiling oil going beyond the heated zone while also converting a substantial proportion into lower boiling oils and wherein the condensate is redistilled to recover the low boiling oils formed and residual high-boiling oils, said residual high boiling oils being then retreated in the same manner; allas more fully hereinafter setforth and as claimed. The main source of aromatic orcylic hydrocarbons is coal tar or coal gas, produced by th'e'destructive distillation of coal. The

commercial demand is largely for the lower boiling'oils, benzene (benzol) and toluene while there is. much less. demand for the higher boiling oils which consequently sell at a much lower price. I have found that I can cheaply\ and readily convert these' higher boiling oils into'lower-boiling oils of greater value by a process which in substance consists in boiling oils by heat under carefully regulated conditions.

While thepresent process is applicable to other aromatic materials of high boiling point, I regard it as particularly useful .in the treatment of what is known commercially as solvent naphtha; a neutral coal tar distillate boiling for the most part between 130 and 180 C. I shall therefore hereinafter discuss this material more specifically.

The present process may however be applied eaking up the vapors of such high- Specification of Letters Patent. Patented J une 26, 1917. I Application filed November 10, 1915. Serial No. 60,746. i

On passing solvent naphtha vapors through a hot tube or retort, the results vary according to conditions; but there is always a breaking down of the contained high boiling hydrocarbons with the production of gas, tarry materials and low boiling hydrocarbons in varying proportions. Since it is the low-boiling hydrocarbons which are desired, production of gas and tarry materials is, for the-present purposes, a waste; and conditions must accordingly be provided wherein the production of gas and tarry materials is as small as possible.

As I have found, the ratio of gas and tar to hydrocarbons depends largely upon the temperature and upon the rate of feed; or, in other words, upon the time factor; the time during which the vapors are exposed to the temperature chosen. For example at higher temperatures more rapid rates of oil feed must be used in order to obtain results equivalent to those at lower temperatures. In some ways the use of higher temapparatus is thereby increased. The temperature may range between600 and 1000 G, but as a general rule I find temperatures around 800 0. best adapted. The best rate of feed will of course depend in a measure upon the particular apparatus used in performing the process; but the best rule, and one which is generally applicable, is to feed the solvent naphtha or its vapors to the reaction zone, which may be in a heated tube or retort of any kind, at such'a rate that the eflluent gases and Vapors on condensing in any ordinary way, as by the use of cooling water etc., will give a liquid condensate of at least 70 per cent.'of the volume of the original solvent naphtha. The condensate should also upon redistillation give about a third of its volume of oils having the same into low boiling hydrocarbons a substantial any of the usual types of apparatus. It

portion of it still remains as high boiling hydrocarbons, say about 30 per cent. of the original volume. With a less rapid rate of} feed, the proportion of gas and tar goes up' unduly. But as stated, in operating the process much depends upon the particular apparatus used' since obviously with a long heated zone the conditions are quite. difierent than with a short heated zone and feedconretort having fromburning oil or gas,

. the volume of the solvent naphtha used is i ture.

ditions must be correspondingly changed.

Any suitable heating apparatus permit:

ting transit of vapors therethrough may be employed; such as an iron or clay tube or inlet means at one end and butlet means at the other, the outlet means being connected to any suitable-condenser." The tube or retort may be vertical or horizontal; 'but'I prefer a vertical retortor tube- 'with atop feed thereby obviating dangers of Stratification. Any suitable heating means,

such as fire' heat, electrical heat, flame heat The waste gas of the'operation may be used in heating. This process may at atmospheric pressure or at a pressure above or below atmospheric pressure. Opstation at atmospheric pressure gives very good results.

The solvent naphtha or other high boiling aromatic hydrocarbon may be introduced into the tube-or retort as a'sprayed liquid condensate of about per cent. of

recovered. Such efilu'ent gases and vapors are cooled and the liquid condensate separated from the gas. This gas contains a con-- siderable amount of vapors of benzol and I toluol even where the coolingin 'condensa-' treated in the well understood ways with:

"wash;oil= (high boiling petroleum distillates) -to' absorb .the benzene and toluene which are subsequently boiled oil I and retion is to a low degree. The gas may be covered. Theliquid condensate is distilled will ordinarily give 20 to 25 per cent. ofma- A teri al boiling betweenand 130 C. which "1.,m'ay be condensed and redistilled for benfzene and toluene in the'usual way. It will ordinaril ,give about 30 per cent. of high boiling oilmuch like the original oil; This high boiling oil isdistilled over and returned to the heating zone alone or with new solvent naphtha. There 'will be about 20 tion; which etc. may be adopted.

be carried out per centfof'a tarry residue containing naphthalene,diphenyl, etc. These. may berecovered and utilizedi The high boiling frac- It will be seen, that in the described opera-.

tion, I am running solvent naphthavapors through a heated zone at such arate that about a third of the liquid remains .of theoriginal boiling .point and this third is reis re-run, on again heating in the same manner gives a somewhat hlgher' (l yield of low boiling fractions than before. 7

covered andfrerun together with new solvent'naphtha. f Ontreating 'cresote oils and other mixed coal tar products'in the same way somewhat more complicated condensates are obtained;

these condensates containing not only low boiling hydrocarbons derived from the high boiling hydrocarbons but also low boiling phenols. These low boiling phenols may he separated from the condensate and the low boiling hydrocarbons therein contained,

arlyfof the usual ways...

What I claim is lae'lhe process ofconverting high boiling ing the vapors of such high boiling hydrocarbons through a heated zone ma ntained at a cracking temperature at a rate so rapid as to give a substantial proportion of'un- I, changed high boiling hydrocarbon of the.

original boiling point passing such zone.

2. The process of converting high boiling aromatic hydrocarbons into low boiling arof9o aromatic hydrocarbons into low bo ling aro- 1 matic' hydrocarbons which comprises pass-1 matic hydrocarbons which comprises passing vapors of solvent naphtha through a heated zone maintained ata cracking temperature at a temperature of 600 to 1000 C. and at a rate sufiiciently rapid to give a condensate having about 70 per cent. the: volume of the original solvent naphtha and 1 containing high boiling oils.

3. The process of making benzene and" i toluene from solvent naphtha which comprises passing the vapors of such solvent naphtha through a zone heated to 600? to 1000 ing high boiling oils, condensing the so treated vapors, separating benzene and toluf enle therefrom, and recovering high boiling 01s.".

toluene from high, boiling aromatic oils which comprises passing a mixture of vapors of once run high boiling oil and of fresh high boiling oil through a heated zone at atemperature ofv 600,.,to 1000 (1., re-

covering highboiling oils from such condensate and returning the recovered high let G. at a rate sufficiently rapid to give I v a large volume of liquid condensate -'contain- 4; The process a making-"benzene ad boiling oils together with afresh portion of highboiling oil to the heating zone for re- 5. The proces of converting high boiling i aeo eve aromatic hydrocarbons into low boiling aromatic hydrocarbons which comprises passing vapors of solvent naphtha through a heated Zone at a temperature of about 800 C. and at a rate sufficiently rapid to give a condensate having about 70 per cent. the volume of the original solvent naphtha and containinghigh boiling oils.

6. The process of making benzene and toluene from solvent naphtha Which comprises passing the vapors of such solvent naphtha through a zone heated to about 800 C, at a rate suficiently rapid to give a large volume of liquid condensate, condensing the so treated vapors, separating benzene and toluene therefrom, and recovering high boiling oils.

7. The process of making benzene and toluene from high boiling aromatic oils which comprises passing a mixture of once run high boiling oil and fresh high boiling oil through high boiling oils therefrom and .the recovered high boiling oils for admixa heated zone at a temperature of about 800 0., recovering high boiling oils from such condensate and retumin the recovered high boiling oils together w th a afresh portion or" high boiling oil to the heating zone for re-running.

at a rate suificiently rapid to insure a substantial portion of such vapors passing through unchanged, condensing the so treated vapors,'separating low boiling constituents from the condensate, recovering returning ture with fresh solvent naphtha to produce the described mixture.

In testimony whereof it afix my signature. 1

curve at anarraunnn. i 

